Method of manufacturing tubular metal castings.



'H. BROSGH. METHOD OF MANUFACTURING TUBULAR METAL GASTINGS.

, APPLIOATION FILED MAR. 28, 1914.

Patented Sept. 22, 1914.

the several HUGO BROSCH, or IENNA, AUSTRIA-HUNGARY.

' METHOD or MANUFACTURING TUBULAR METAL cAs'TINes.

Specification of Letters Patent.

I Patented Sept. 22, 1914.

' Application filed March as, 1914. Serial No. 827,969..

To all whom it may concern Be it known that I, HUGO BROSCH, a subject of the Emperor of Austria-Hungary, residing at Vienna, Austria-Hungary, have invented a new and useful Improvement in Methods of Manufacturing Tubular Metal Castings, of which the following is' a specification.

Hitherto metal tubes andtubular metalcastings of slightly ductile metals, as iron, copper, bronze, brass andthe like could not be cast upon rigid or metal cores; if nevertheless in exceptional cases, as in the manufacture of gun-barrels according to the socalled Uchatius-process, rigid or, metal cores are used it is necessary to remove the core from the casting by boring the same. A well knownprocess consists in using metal cores which can 'be taken to pieces; such cores produce spurs or burs and the removal thereof is Very tedious and expensive. For these reasons in the manufacture of metal tubes and tubular metal-castings the use of cores consisting of sand, loam and the like has been found indispensable. Such. cores, however, are not sufficiently rigid and are therefore crushed by the contracting castingmetal. In consequence of the cast metal flowing again to the crushed portions of the core there result wastes or blow holes in the casting. Owing to the slight rigidness of sand and loam cores the thickness of the tubes or tubular castings is not uniform at ortions. In removing the cores they must e destroyed and they therefore can be used only once; Further the inner surface of the metal-casting is always rough and puckered.

The present invention relates to the manufacture of metal-castings and particularly of metal tubes and tubular metal-castings and has for its object to enable the use of rigid or metal cores, which may be used many times. The improved process consists in coating a metal core before the casting with a lubricant or grease which will not melt at the working temperaturesemployed and which enables the core to slide within the solid metal-casting so that after the castthe core.

preparation of materials for coating a mold core, for the purpose described.

The invention will be described .in connection with the accompanying drawingsin which the casting-mold is shown in the Figures 1 and 2 in vertical sectional View, and in plan, respectively.

The casting mold made of cast-iron con sists of two upper parts-a and a bottom part b and is provided with a core-guide c having a bore, in which fits the extension (Z of the core e. The core 6 is made of steel and isprovided with a bore f. On the upper end of the bore f there is provided a screwthread into which a strong metal rod serving to withdraw the core is screwed after the casting. The core is coated on its cylindrical surface and on its bottom face with a thin layer it of lubricant or grease, rendering the core movable within the solid metalcasting. In the upper end of the mold a there is inserted an annular guiding collar 71 which by four projections 7' holds the core 6 inv upright position. The liquid metal is admitted to the mold through the four openings is situated between the projections j. A plate Z serves to cover the mouth of the bore f.

Suitable materials for coating the rigid or metal core to render it removable from the casting are obtained by adding magnesium-silicates to a suitable ground-mass, consisting for example of a mixture of mineral-oil, soot-black, linseed-oil and plumbago. By coating a metal core with such composition, it is rendered smooth and of such nature that the'cast metal will not adhere thereto so that the core may be readily withdrawn bodily from the casting. During the casting operation, or prior thereto,

the binding oil or combustible portion ofthe mixture maybe consumed but the magnesium silicates-will not be affected. The several materials of the mixture are so thoroughly intermixed that even when the binding elements thereof, affected by heat,

are destroyed the magnesium silicates will form a smooth coating over the surface of Such material does not affect the surface of the casting coming in contact therewith, so that the inner surface of a cast tube, for example, will besmooth and free from ridges or depressions due to the action of the core casting thereon. The described method enables the use of rigid or metal cores in many cases where such a use has been hitherto impossible, and it'has the advantage that the'core may be used many times. Metal tubes and tubular metal-castings made according to the improved process have walls of uniform thickness. Owing to the use of metal-cores th'e cast metal obtains a great compactness and fineness of struclatter advantage is especially important for metals like bronze and brass, containing copper and having great tendency for welding,

I claim: 1. The herein described improvement in the method of manufacturing .a tubular metal body in a mold having a rigid, bodily removable, core comprising initially coating the core with a mixture comprising a suitable binder and magnesium silicates, foithe purpose specified. c 7 2. A coating for rigid, 'bodilyl removable,

tubular cast metal bodies adapt'edto render the core readily removable when the cast metal has solidified sufliciently to retain the cores of molds-,for' use in manufacturing I I cates, mineral oil, soot-black, linseed oil and plumbago.

HUGO BROSCH.

Witnesses: JOSEPH C. STADLER,

AUGUST FUGGER. 

